The invention relates to an in-line filter provided with a substantially elongated filter housing in which filtering material is included, the filter housing being provided on a first end with an inflow opening and on a second, opposite end with an outflow opening, while at the inflow opening and the outflow opening fastening means are provided for fastening a supply or discharge tube, respectively.
Such filters have been known for years and are put into circulation by, inter alia, Supelco Inc. of Bellefonte, Pa., USA.
The drawback of these known filters is that the fastening means are designed as ferrule fittings, also indicated in commerce as Swagelok® fittings. When detaching the filter from the supply and discharge tube, the ferrule fittings are loosened and the supply and discharge tubes are in open communication with the atmosphere. This means that the tube system becomes polluted and that after changing the filter, rinsing with carrier gas such as, for instance, nitrogen is to take place for a long time, sometimes even a few hours in order to clean the tube system before a downstream process, such as, for instance, a detection process such as, for instance, gas chromatography, mass spectrography or an LCMS process can be put in fluid communication with the tube system again.
Another drawback of the known in-line filters is that, after coupling and uncoupling a number of times, the clamp fittings damage the supply and discharge tubes. The tube then needs to be shortened somewhat to allow an undamaged part thereof to be connected to the clamp fittings. It will be clear that this shortening is only possible a number of times and that after this, at least a partial replacement of the supply and/or discharge tube is required. In particular for the laboratory personnel having to perform these relatively technical operations, this is often an awkward, and in any way time-consuming task.